Q-inQ questions

Unanswered Question
Dec 13th, 2007

Hi all,

i've got some questions about QnQ:

1 command 'set dot1q-all-tagged enable' do you think can create disruption in traffic?

2 is jumbo frames enough 1504 Bytes?

3 how can i assign a VLAN to a tunnel?

i'll add a attachment for clarify situation, vlan 2-3-4-5-6 must not see other vlan on switch A-B-C-D and switch A-B-C-D must see each other VLAN 9-10-11-12.

can i transport also vlan 8-9-10-11 in dot1q mode (i need those VLAN in devices A-B-C-D) or i need to encapsulate in Q-inQ? Link intra switches (trunk all) needs sono change (jumbo frames)? if link 1 died is trunk all able to transpost all the stuffs?

Thanks a lot for an answer, and thanks anyway for attention :)


I have this problem too.
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cisco_lad2004 Sat, 12/15/2007 - 10:46

1-I have not tested this, but I think good chance it might be disruptive ( because of transition to tagging all frames).


2-some platforms supports 9216Bytes.

3- 50 Outer VLAN, 10& 20 InnerVLANs

Router# configure t

Router(config)# interface gigabitethernet3/0.10

Router(config-subif)# encapsulation dot1q 50 second-dot1q 10

Router(config)# interface gigabitethernet3/0.20

Router(config-subif)# encapsulation dot1q 50 second-dot1q 20

Vlan10& 20 will not be seen on A-B-C-D.

Vlan 50 is then treated as a normal VLAN u can trunk over Link1 and Link2. U obviously need to enable SPT/RSPT. redundancy will take care of itself here. If u want a higher response use RSTP.




danilo.dicesare Sun, 12/16/2007 - 00:26

THX very much....also in CatOS i can do same thing?

How do i have t treath native VLAN?

have nice day



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